NickLippert,
If you look at the file system with a file manager app you will see a folder that emulates an SD card. This is where user data is stored. I don't know why it would show the battery usage you are getting.

I'm getting a lot of battery loss for SD card, I wonder what is causing that.

I was looking around in my storage and saw that dolphin had almost 3gb of data in the "Tunny browser" folder. I deleted all of that and the weird battery loss as gone away. My phone had also started to get a little slower recently and clearing that folder helped too.